I want to convert a value entered in a textBox (which can only be empty or "1" or "2" or "3") to an integer. If empty I want it to be 0, otherwise, it's corresponding value (1, 2, or 3).
Is there a way to do that like:
MyIntVal = TryConvertToInt(textBox1.Text, 0);
...where an empty string or anything not readily convertible to an int would default to 0?
You can use the Int32.TryParse Method:
int myIntVal;
if (!int.TryParse(textBox1.Text, out myIntVal))
{
myIntVal = 42;
}
If the method returns false, the text could not be parsed. myIntVal will be 0 in this case; you can assign a different default value to your variable as shown above.
int result = 0;
int.TryParse(stringValue, out result);
Will default to 0 if stringValue cannot be parsed to an int.
http://msdn.microsoft.com/en-us/library/f02979c7.aspx
There's the static TryParse. It returns true if it works.
int myIntVal;
int.TryParse(textBox1.Text, out myIntVal);
Related
This question already has answers here:
Input string was not in a correct format
(9 answers)
Closed 3 years ago.
C# CODE
I have a problem with my "Check in" form.
I want to multiply the txtsubtotal and txtadvancepayment.
In textchange if I put number on the txtadvancepayment, the overallresult is correct. But if I clear the txtadvancepayment (Incase when the user puts a wrong value) it would be error. The error says "Input string was not in a correct format."
What should I do?
My Code downward
int overalltotal = 0;
int a = Convert.ToInt32(txtsubtotal.Text);
int b = Convert.ToInt32(txtadvancepayment.Text);
overalltotal = a - b;
txttotalbalance.Text = overalltotal.ToString();
An empty string cannot be parsed as an int. As others have mentioned, you can use int.TryParse which accepts a string as the first parameter and an out int as the second parameter, which holds the parsed value. You could do this:
int overallTotal = 0;
int a = 0;
int b = 0;
// TryParse returns a bool
// If either of these fails, the variable a or b will keep the default 0 value
int.TryParse(txtSubtotal.Text, out a);
int.TryParse(txtAdvancePayment.Text, out b);
// Sum a and b
overallTotal = a + b;
If you want to show an error to the user that one or both fields isn't a valid integer, you can assign a bool variable such as var aIsNumber = int.TryParse(...) and then check if aIsNumber or bIsNumber is false. If so, then a and/or b could not be parsed to an int.
You could use Int32.TryParse.
Int32.Parse attempts to convert the string representation of a number to its 32-bit signed integer equivalent and returns value indicates whether the operation succeeded. This would mean, in case your textbox is empty or contains a invalid numeric representation, and the method would return false since it would not be able to convert it to int32
For example
if(Int32.TryParse(txtsubtotal.Text,out var a)
&& Int32.TryParse(txtadvancepayment.Text,out var b))
{
// Code which requires a and b
}
Im using the Mahapps.Metro framework for my C#, Wpf Application.
In the framework is the wpf element: NumericUpDown.
Now I used the element like this:
<Controls:NumericUpDown Name="numCreateArticleStock" Minimum="0"/>
Now I want to convert the entered value in the field into a int value.
Here is my try:
int articleStock = 0;
if(!Int32.TryParse(numCreateArticleStock.Value, out articleStock)
{
await this.ShowMessageAsync("Error", "Error - Message");
}
I get this error:
Cannot convert "double?" in "string"
Maybe someone of you have an Idea, Thanks!
The error you get is because the TryParse method expects as string value, but you have a double? value.
There is no need to parse the value, you can just convert it from double:
int articleStock = (int)numCreateArticleStock.Value.GetValueOrDefault();
The GetValueOrDefault method will turn a null value into 0, I assume that's what you want when there is no value to get from the control.
Since numCreateArticleStock.Value is a double? why not just check if it is null and then cast it to int if it is not null.
int articleStock = 0;
if(!numCreateArticleStock.Value.HasValue)
{
// value is null decide what to do in that case.
}
else
{
articleStock = (int)numCreateArticleStock.Value.Value;
}
This is my enumeration:
enum Stations
{
Central,
RomaStreet,
Milton,
Auchenflower,
Toowong,
Taringa,
Indooroopilly
};
this is my code:
static string DepartureStation(){
string departStationinput;
string departStation;
if (departStation == null){
Console.WriteLine("Please Enter one of the names of the stations listed above! ");
departStationinput = Console.ReadLine(); // Gets String
departStation = departStationinput.ToUpper(); // Converts String into UPPER CASE
/*Need to check if the string is matched in the ENUM and return a variable/Value for it*/
}
return departStation;
}
You can use Enum.IsDefined method then parse the value:
if(Enum.IsDefined(typeof(Stations), departStationinput)
{
var value = Enum.Parse(typeof(Stations), departStationinput);
}
Or you can use Enum.TryParse directly:
Stations enumValue;
if(Enum.TryParse(departStationinput, out enumValue))
{
}
If you want to ignore case sensitivity there is also another overload that you can use.
First of all, about integer position, it depends on what you expect as integer position:
It may be the enumeration integer value.
The index of the enumeration value.
If you want the integer value, it's about doing this:
int value = (int)Enum.Parse(typeof(Stations), "Central"); // Substitute "Central" with a string variable
In the other hand, since enumeration values may not be always 1, 2, 3, 4..., if you're looking for the index like an 1D array:
int index = Array.IndexOf
(
Enum.GetValues(typeof(Stations))
.Select(value => value.ToString("f"))
.ToArray(),
"Central"
);
var val = Enum.Parse(typeof(YourEnumType),name);
I have the following code
Call.Direction CallDir = details.dir;
and the output is either In or out.
my question how can I convert the output to be as follow:
if CallDir value is In ===> display 0
if CallDir value is Out ===> display 1
Okay, so if you wanted to return a different value based on the enum, just do this:
return CallDir == Call.Direction.In ? 0 : 1;
However, if what you're saying is details.dir is a string of In or Out and you need to get that into an enum, then do this:
Call.Direction CallDir;
if (!enum.TryParse<Call.Direction>(details.dir, out CallDir))
{
// set it to some default value because it failed
}
In addition to what Michael said, if your enum is defined with the appropriate values, you can simply cast it to an int.
enum CallDirection { In = 0, Out = 1 }
var dir = CallDirection.In;
Console.Write((int)dir); // "0"
I have this code that it works only if all the textBox contains values.. But if a textbox is empty i get an error..
Int32 Total = Int32.Parse((txtChild1.Text))
+ Int32.Parse(txtChild2.Text)
+ Int32.Parse(txtChild3.Text)
+ Int32.Parse(txtWife1.Text)
+ Int32.Parse(txtWife2.Text)
+ Int32.Parse(txtWife3.Text);
I know that it must be a function like IsNull but for the integer values..
Does anyone know what it is ?
You're looking for Int32.TryParse:
Int32 val;
if (Int32.TryParse(txtChild1.Text, out val)){
// val is a valid integer.
}
Which you call on every .Text property, then add them together. You can also make an extension to make it easier (if you chose):
public static class NumericParsingExtender
{
public static Int32 ToInt32(this String input, Int32 defaultValue = 0)
{
if (String.IsNullOrEmpty(input)) return defaultValue;
Int32 val;
return Int32.TryParse(input, out val) ? val : defaultValue;
}
}
Then, in practice:
Int32 total = txtChild1.Text.ToInt32() + txtChild2.Text.ToInt32()
+ txtChild3.Text.ToInt32() + /* ... */;
And, of course, an example
You can use Int32.TryParse:
Int32 int1 = 0;
Int32.TryParse(txtChild1.Text, out int1);
//.... more int declarations
Int32 total = int1 + int2 + int3; //etc. etc.
TryParse will try to parse the text and if it fails, it will set the variable to 0.
You can also inline some of the logic (although this makes the code very long and messy):
Int32 Total = (txtChild1.Text.Length == 0 ? 0 : Int32.TryParse(txtChild1.Text)) + (txtChild2.Text.Length == 0 ? 0 : Int32.TryParse(txtChild2.Text)); //etc. etc.
Int32.TryParse reference: http://msdn.microsoft.com/en-us/library/f02979c7.aspx
Shorthand if reference: http://msdn.microsoft.com/en-gb/library/ty67wk28(v=vs.110).aspx
you should check if the TextBox is not empty before parsing it or you can use TryParse
http://msdn.microsoft.com/en-us/library/f02979c7.aspx
Int32 is a value type. It can't be null. Or course there is a nullable types but hey..
Try with Int32.Tryparse() method.
Converts the string representation of a number to its 32-bit signed
integer equivalent. A return value indicates whether the operation
succeeded.
Int32.TryParse(txtChild1.Text, out val)
returns boolean true if s was converted successfully; otherwise, false.
You can't parse an empty string "". Check if the box contains anything before parsing.
Textbox.text != ""
Other answers are quicker to use tryparse is the best in fact, as it does the same with less lines of code!